The Apache HTTP server is the most popular web server in use on the Internet [1]. The first version appeared on the market two decades ago, in April 1995. Due to constant development efforts by the Apache Software Foundation, the server is still in use today. It is known for its modular architecture as well as its rich functionality.

However, the competition has not been asleep. For example, the market share of Nginx has been growing quite a bit in the past few years. As a result, one goal of the Apache Software Foundation is to improve performance of the Apache HTTP server to ensure that its performance compares well with Nginx. And, in fact, version 2.4 has caught up somewhat in terms of performance.

This becomes apparent when comparing the performance of consecutive versions of the Apache web server running on Debian Wheezy (2.2.22) and Debian Jessie (2.4.10). Figure 1 shows that version 2.4 processes one million requests at a rate that is about 20 seconds faster than the previous 2.2 version.

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